Polymeric materials, including thermoplastics and thermosets, are used extensively in automotive vehicles and for other purposes. They are light and relatively easy to fashion into complex parts, and are therefore preferred instead of metals in many instances. However a problem with some polymers is salt stress (induced) corrosion cracking (SSCC), where a part under stress undergoes accelerated corrosion when under stress and in contact with inorganic salts. This often results in cracking and premature failure of the part.
Polyamides such as polyamide 6,6, polyamide 6, polyamide 6,10 and polyamide 6,12 have been made into and used as vehicular parts and other types of parts. While it has been reported that polyamides 6,10 and 6,12 are more resistant to SSCC (see for instance Japanese Patent 3271325B2), all of these polyamides are prone to SSCC in such uses, because for instance, various sections of vehicles and their components are sometimes exposed to salts, for example salts such as sodium chloride or calcium chloride used to melt snow and ice in colder climates. Corrosion of metallic parts such as fittings and frame components made from steel and various iron based alloys in contact with water and road salts can also lead to formation of salts. These salts, in turn, can attack the polyamide parts making them susceptible to SSCC. Thus polyamide compositions with better resistance to SSCC are desired.
U.S. Pat. No. 4,076,664 discloses a terpolyamide resin that has favorable resistance to zinc chloride.
Plasticized long chain polyamides play an important role in the automotive tubing market. Long chain polyamides, that is, a polyamide derived from at least one monomer unit having at least 10 carbon atoms connected in a linear array, are known for having good salt resistance. Salt resistance is a necessary quality in many automotive parts, due to components exposure to the winter salting conditions. The drawback of plastification is that it decreases the salt resistance of long chain polyamides such as PA1010, PA12, PA11.
U.S. Pat. No. 7,750,110 B2 discloses flexible semicrystalline polyamides useful for manufacturing parts by extrusion or injection molding including polyamide blends and plasticizers.
The objective of the invention is to improve the salt resistance of sulphonamide plasticized long chain nylons.